The present invention relates to a bleed deflector for use in a gas turbine engine.
Current high pressure compressor bleed discharge designs consist of either a tube or a vaned deflector which directs high temperature engine bleed air into a fan duct. Such an arrangement often leads to structural problems caused by the bleed air plume impacting the inner and outer fan duct walls, exceeding their temperature limits. Typical bleed discharge air is up to 800xc2x0 F. to 1000xc2x0 F., while fan air is up to 240xc2x0 F. Duct material temperature limits are on the order of 300xc2x0 F. to 350xc2x0 F.
In the past, a silencer for high velocity gas flow in a gas turbine engine has been proposed. One such silencer is shown in U.S. Pat. No. 4,537,277 to Bryce. As shown therein, the Bryce silencer includes a flow passage and a domed perforated plate which terminates the flow passage. The perforated portions of the plate are distributed over the plate so as direct gas from the passage as a plurality of divergent jets, so that noise is produced with a frequency at maximum intensity in a range of the audible spectrum at which human auditory perception is relatively insensitive. The domed plate portion of the silencer is mounted flush with the inner wall of the bypass duct.
It has been found that devices which utilize flush outlets cause inner duct wall burns because cooler fan air cannot get immediately downstream of the outlet to dilute the hot discharge flow from the device.
Attempts have been made to develop a bleed deflector which avoided the problem of inner duct wall burns. One such attempt is shown in FIGS. 1 and 2. In this bleed deflector, an aerodynamically shaped deflector 10 has outlets 12 in its side walls which separate the bleed air discharge into two lateral plumes 14 and 16. Each of the outlets 12 has discrete holes which can be angled to direct the jets in a desired direction. This deflector however did not work because it was not possible to jet enough flow out of the bleed deflector. This, there remains a need for a bleed deflector which adequately discharges the bleed air from a compressor of a gas turbine engine.
Accordingly, it is an object of the present invention to provide an improved bleed deflector for use in a gas turbine engine.
It is a further object of the present invention to provide a bleed deflector which substantially eliminates wall burns in a fan duct.
The foregoing objects are attained by the bleed deflector of the present invention.
In accordance with the present invention, a bleed deflector broadly comprises an inlet portion for receiving bleed air, an outlet portion for discharging the bleed air into a duct, and means for positioning said outlet portion above an inner wall of the duct and for creating a linear flow path for the discharge air between the inlet portion and the outlet portion.